Should the contractor fail to perform the work to the satisfaction of the surveyor, he then shall have power to execute the work and charge the same to the contractor, and deduct the cost from any amount that may be due to him; and in the event of the cost being more than the amount due, or if there shall then be no sum due to the contractor, such cost shall be paid by the contractor to the mayor, aldermen, and citizens, and the same shall be recoverable from him as liquidated and ascertained damages. _Caithness Flagging_ is now used very largely instead of Yorkshire; it comes from Thurso in Scotland, and it is contended for it that it possesses many excellent qualities, amongst others may be enumerated the following: (1). It is impervious to wet. (2.) It is not slippery nor does it wear so. (3.) It does not scale or flake. (4.) It dries rapidly after rain. (5.) Its appearance is cheerful. (6.) Great durability, as it does not abrade. (7.) Frost has no effect upon it. (8.) Can be re-used when half worn. (9.) Cleanliness; for, not being porous, no dirt or dust can adhere to it. (10.) Vehicular traffic may be turned over it without injury to the path. (11.) Economy; as natural forces can be used, thus saving labour, and it can be laid from 1¹⁄₂ to 2 inches thick only. (12.) Having sawn edges, the joints are expeditiously and well made. (13.) Its whole surface wears evenly. The following table was compiled by the well-known firm of Kirkaldy, by direction of Mr. Tarbotton the Borough Engineer of Nottingham, in order to ascertain the resistance to a gradually increased bending stress upon Yorkshire flagging as compared with Caithness.